In OFDM (Orthogonal Frequency-Division Multiplexing) communication, PAPR (Peak-to-Average Power Ratio) becomes higher as FFT (Fast Fourier Transformation) size is increased.
A literature 1 (Unexamined Japanese Patent Application Kokai Publication No. 2006-165781) discloses an OFDM communication apparatus controlling the phase of subcarrier modulated signal based on the optimum phase calculated by a sequential decision procedure, prior to IFFT (Inverse Fast Fourier Transformation) in order to reduce the PAPR. On the other hand, a literature 2 (Daiji Motokawa, Eiji Okamoto, Yasunori Iwanami, “A channel estimation scheme with a peak-to-average power ratio reduction in single carrier-frequency domain equalization using sparse pilot symbols” Technology Study Reports of The Institute of Electronics, Information and Communication Engineers, RCS Wireless Communication System, The Institute of Electronics, Information and Communication Engineers, August of 2009, Vol. 109, p 165-170) discloses a technique of reducing the PAPR by applying a pilot signal is a CAZAC (Constant Amplitude Zero Auto-Correction) series to SC (Single Carrier) transmission.